The Celsius took a three-degree tumble after climbing to a post-Christmas high on Monday, the change in course triggered by a high-pressure belt that is now channelling the North Wind towards Calcutta.
The nip in the air that made people pile on the woollens on Tuesday morning would stay till at least Friday, the weather office said.
The wind had picked up pace around midnight on Monday, hitting 8kmph at 8.30am. The reading was the same at 11.30am. Even at 2.30 in the afternoon, the wind speed was a steady 6kmph.
On Monday, the minimum temperature had touched 16.4 degrees, two notches above normal and the highest since Christmas Eve. By Tuesday morning, it was down to 13.1 degrees, a notch below normal.
The maximum temperature fell from 24.4 to 22.4 degrees Celsius, five degrees below normal. “The brisk northerly wind is likely to continue for the next two to three days. For now, Calcuttans can enjoy the chill,” said G.K. Das, a meteorologist at the Regional Meteorological Centre in Alipore.
The maximum temperature had dropped below 20 degrees Celsius in the middle of last week too, though that was mainly because of a tall layer of advective fog that kept the sun out.
The temperature recorded at the Alipore observatory at 8.30am on Tuesday was 14.8 degrees Celsius, which meant that factoring the wind, people would have then felt as cold as they would if the temperature was 12.8 degrees.
“There is a term called real-feel temperature to determine how cold the human body feels at a particular time. Given the conditions on Tuesday morning, that reading was two degrees lower than the actual temperature,” a senior official of the India Meteorological Department said.
By 11.30am, the sun was stronger and the temperature rose to 19.4 degrees but the breeze was still strong enough to keep a sweater on.
“I was in a full-sleeve sweater despite the bright sunshine and I did not feel uncomfortable,” said Richa Ghosh, 25.
Meteorologists said the current flow of the northerly wind was because of a high-pressure belt over Jharkhand and Bihar. “Since the atmospheric pressure on the surface is greater than that of its surrounding environment in a high-pressure belt, winds flow outwards. Calcutta is, therefore, benefiting from that system,” the IMD official said.
So is there a chance of the city yet experiencing a day or two of sub-10 temperature? Unlikely.
“There is little chance of the Celsius dropping below 13 degrees in this phase because north India itself isn’t very cold as of now,” the official said.